Fusion unleashes vast amounts of energy that might one day be used to power giant electrical grids. But the laboratory systems that seem most promising produce radiation in the form of fast-moving neutrons, and these present a health hazard that requires heavy shielding and even degrades the walls of the fusion reactor. Physicists have now produced fusion at an accelerated rate in the laboratory without generating harmful neutrons (abstract). A team led by Christine Labaune, research director of the CNRS Laboratory for the Use of Intense Lasers at the Ecole Polytechnique in Palaiseau, France, used a two-laser system to fuse protons and boron-11 nuclei. One laser created a short-lived plasma, or highly ionized gas of boron nuclei, by heating boron atoms; the other laser generated a beam of protons that smashed into the boron nuclei, releasing slow-moving helium particles but no neutrons. Previous laser experiments that generated boron fusion aimed the laser at a boron target to initiate the reaction. In the new experiment, the laser-generated proton beam produces a tenfold increase of boron fusion because protons and boron nuclei are instead collided together directly.
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